1. Field of the Invention
The present invention relates to a method for operating a wireless network, especially a Wi-Fi technology based network, wherein the network is comprising at least one wireless device for transmission of data and wherein the device may use a data or frame aggregation technique to provide an adjustable amount of aggregation. Further, the present invention relates to a wireless network, especially a Wi-Fi technology based network, wherein the network is comprising at least one wireless device for transmission of data and wherein the device may use a data or frame aggregation technique to provide an adjustable amount of aggregation.
2. Description of the Related Art
A method and an according wireless network of the above mentioned type are known from IEEE 802.11n standard, IEEE Standard for Information technology Telecommunications and information exchange between systems Local and metropolitan area networks, for example. The 802.11n technology, by providing higher data rates and several new capabilities at Layer 2, is expected to be the basis of the next generation WLAN networks. According to WFA (Wi-Fi-Alliance), more than 800 products from different market segments (Routers, laptops, printers, TVs, etc.) are already 802.11n certified.
The 802.11n technology offers a variety of physical layer mechanisms for achieving higher throughput and improved packet reception capability. Each 802.11n radio can have multiple transmit and receive antennas. Multiple spatial data streams can be transmitted at the same time, on the same channel, using different antennas, hence resulting in increased data rates. The data streams can be combined from multiple receivers using advanced signal processing techniques.
A key technical feature that 802.11n brings along in order to boost the performance of Wi-Fi networks, is a reduction in the MAC (Media Access Control) access overhead by means of frame aggregation techniques. In particular, two mandatory aggregation methods, namely A-MPDU (Aggregation of MAC Protocol Data Unit) and A-MSDU (Aggregation of MAC Service Data Unit), have been defined in 802.11n, that allow to embed several higher layer packets (MSDUs) into a single MAC frame (MPDU), and also several MAC frames into a single physical frame. The particular method that a Wi-Fi device could use to decide which frames to aggregate though, is not specified in the 802.11n standard in order to allow vendor differentiation.
The main reasoning behind the frame aggregation techniques included in 802.11n was to improve the throughput of a TCP (Transmission Control Protocol) transfer over Wi-Fi, where in a typical setting the buffer in the AP (Access Point) is filled with TCP packets that can be easily aggregated in order to increase efficiency. Notice that aggregation greatly improves performance in the case of TCP because many packets can be transmitted into the wireless medium with a single backoff access, instead of doing a backoff access per packet as in current Wi-Fi networks.
However, it is not clear whether real-time communications like Voice or Video can benefit from these aggregation techniques. The reason is that this type of communication typically generates data in a periodic fashion, e.g. 20 ms for a G.711 Voice codec, and have tight delay requirements. Therefore, in the case of real-time communications, data packets are usually sent as soon as possible, which reduces the possibility of building efficient aggregations.